Ventilating attics to minimize icings at eaves

Abstract In cold regions, icicles and ice dams may develop on roofs that slope to cold eaves. Ventilating the space below the snow-covered roof with outdoor air to create a ‘cold’ ventilated roof is often an effective way to avoid such problems. Several buildings in northern New York were instrumented to determine how their attic temperature influenced icing. We observed that problematic icings developed very slowly, if at all, when the outside temperature was above −5.5 °C. It appears that icings can be avoided by sizing natural, and if necessary, mechanical attic ventilation systems to maintain an attic temperature of −1 °C when the outside temperature is −5.5 °C.